// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2008 Gael Guennebaud <gael.guennebaud@inria.fr>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifndef EIGEN_SCALING_H
#define EIGEN_SCALING_H

namespace Eigen {

/** \geometry_module \ingroup Geometry_Module
 *
 * \class UniformScaling
 *
 * \brief Represents a generic uniform scaling transformation
 *
 * \tparam _Scalar the scalar type, i.e., the type of the coefficients.
 *
 * This class represent a uniform scaling transformation. It is the return
 * type of Scaling(Scalar), and most of the time this is the only way it
 * is used. In particular, this class is not aimed to be used to store a scaling transformation,
 * but rather to make easier the constructions and updates of Transform objects.
 *
 * To represent an axis aligned scaling, use the DiagonalMatrix class.
 *
 * \sa Scaling(), class DiagonalMatrix, MatrixBase::asDiagonal(), class Translation, class Transform
 */

namespace internal {
// This helper helps nvcc+MSVC to properly parse this file.
// See bug 1412.
template<typename Scalar, int Dim, int Mode>
struct uniformscaling_times_affine_returntype
{
	enum
	{
		NewMode = int(Mode) == int(Isometry) ? Affine : Mode
	};
	typedef Transform<Scalar, Dim, NewMode> type;
};
}

template<typename _Scalar>
class UniformScaling
{
  public:
	/** the scalar type of the coefficients */
	typedef _Scalar Scalar;

  protected:
	Scalar m_factor;

  public:
	/** Default constructor without initialization. */
	UniformScaling() {}
	/** Constructs and initialize a uniform scaling transformation */
	explicit inline UniformScaling(const Scalar& s)
		: m_factor(s)
	{
	}

	inline const Scalar& factor() const { return m_factor; }
	inline Scalar& factor() { return m_factor; }

	/** Concatenates two uniform scaling */
	inline UniformScaling operator*(const UniformScaling& other) const
	{
		return UniformScaling(m_factor * other.factor());
	}

	/** Concatenates a uniform scaling and a translation */
	template<int Dim>
	inline Transform<Scalar, Dim, Affine> operator*(const Translation<Scalar, Dim>& t) const;

	/** Concatenates a uniform scaling and an affine transformation */
	template<int Dim, int Mode, int Options>
	inline typename internal::uniformscaling_times_affine_returntype<Scalar, Dim, Mode>::type operator*(
		const Transform<Scalar, Dim, Mode, Options>& t) const
	{
		typename internal::uniformscaling_times_affine_returntype<Scalar, Dim, Mode>::type res = t;
		res.prescale(factor());
		return res;
	}

	/** Concatenates a uniform scaling and a linear transformation matrix */
	// TODO returns an expression
	template<typename Derived>
	inline typename Eigen::internal::plain_matrix_type<Derived>::type operator*(const MatrixBase<Derived>& other) const
	{
		return other * m_factor;
	}

	template<typename Derived, int Dim>
	inline Matrix<Scalar, Dim, Dim> operator*(const RotationBase<Derived, Dim>& r) const
	{
		return r.toRotationMatrix() * m_factor;
	}

	/** \returns the inverse scaling */
	inline UniformScaling inverse() const { return UniformScaling(Scalar(1) / m_factor); }

	/** \returns \c *this with scalar type casted to \a NewScalarType
	 *
	 * Note that if \a NewScalarType is equal to the current scalar type of \c *this
	 * then this function smartly returns a const reference to \c *this.
	 */
	template<typename NewScalarType>
	inline UniformScaling<NewScalarType> cast() const
	{
		return UniformScaling<NewScalarType>(NewScalarType(m_factor));
	}

	/** Copy constructor with scalar type conversion */
	template<typename OtherScalarType>
	inline explicit UniformScaling(const UniformScaling<OtherScalarType>& other)
	{
		m_factor = Scalar(other.factor());
	}

	/** \returns \c true if \c *this is approximately equal to \a other, within the precision
	 * determined by \a prec.
	 *
	 * \sa MatrixBase::isApprox() */
	bool isApprox(const UniformScaling& other,
				  const typename NumTraits<Scalar>::Real& prec = NumTraits<Scalar>::dummy_precision()) const
	{
		return internal::isApprox(m_factor, other.factor(), prec);
	}
};

/** \addtogroup Geometry_Module */
//@{

/** Concatenates a linear transformation matrix and a uniform scaling
 * \relates UniformScaling
 */
// NOTE this operator is defined in MatrixBase and not as a friend function
// of UniformScaling to fix an internal crash of Intel's ICC
template<typename Derived, typename Scalar>
EIGEN_EXPR_BINARYOP_SCALAR_RETURN_TYPE(Derived, Scalar, product)
operator*(const MatrixBase<Derived>& matrix, const UniformScaling<Scalar>& s)
{
	return matrix.derived() * s.factor();
}

/** Constructs a uniform scaling from scale factor \a s */
inline UniformScaling<float>
Scaling(float s)
{
	return UniformScaling<float>(s);
}
/** Constructs a uniform scaling from scale factor \a s */
inline UniformScaling<double>
Scaling(double s)
{
	return UniformScaling<double>(s);
}
/** Constructs a uniform scaling from scale factor \a s */
template<typename RealScalar>
inline UniformScaling<std::complex<RealScalar>>
Scaling(const std::complex<RealScalar>& s)
{
	return UniformScaling<std::complex<RealScalar>>(s);
}

/** Constructs a 2D axis aligned scaling */
template<typename Scalar>
inline DiagonalMatrix<Scalar, 2>
Scaling(const Scalar& sx, const Scalar& sy)
{
	return DiagonalMatrix<Scalar, 2>(sx, sy);
}
/** Constructs a 3D axis aligned scaling */
template<typename Scalar>
inline DiagonalMatrix<Scalar, 3>
Scaling(const Scalar& sx, const Scalar& sy, const Scalar& sz)
{
	return DiagonalMatrix<Scalar, 3>(sx, sy, sz);
}

/** Constructs an axis aligned scaling expression from vector expression \a coeffs
 * This is an alias for coeffs.asDiagonal()
 */
template<typename Derived>
inline const DiagonalWrapper<const Derived>
Scaling(const MatrixBase<Derived>& coeffs)
{
	return coeffs.asDiagonal();
}

/** \deprecated */
typedef DiagonalMatrix<float, 2> AlignedScaling2f;
/** \deprecated */
typedef DiagonalMatrix<double, 2> AlignedScaling2d;
/** \deprecated */
typedef DiagonalMatrix<float, 3> AlignedScaling3f;
/** \deprecated */
typedef DiagonalMatrix<double, 3> AlignedScaling3d;
//@}

template<typename Scalar>
template<int Dim>
inline Transform<Scalar, Dim, Affine>
UniformScaling<Scalar>::operator*(const Translation<Scalar, Dim>& t) const
{
	Transform<Scalar, Dim, Affine> res;
	res.matrix().setZero();
	res.linear().diagonal().fill(factor());
	res.translation() = factor() * t.vector();
	res(Dim, Dim) = Scalar(1);
	return res;
}

} // end namespace Eigen

#endif // EIGEN_SCALING_H
